When asked to subject the researcher to a loud noise or to grade the researcher’s performance, the women who watched “Mean Girls” and “Kill Bill” were significantly more aggressive toward the researcher than the control group was. The study suggests that the effect of watching girls engage in indirect bullying of each other, known as relational aggression, is as harmful as watching violent images.

“Everyone’s concerned about violence in the media, as they should be, but we’re missing out on lots of violence out there,” said Coyne, whose study will appear in the November issue of the Journal of Experimental Social Psychology. “We need to look at these other types of aggression out there because we know that they’re having an effect on aggression.”

“Studies show that relational and other nonphysical forms of aggression are just as harmful to a student’s ability to learn, grow and succeed,” writes The Ophelia Project, an organization dedicated to stopping relational aggression. “Relational aggression encompasses behaviors that harm others by damaging, threatening to damage or manipulating one’s relationships with his/her peers, or by injuring one’s feelings of social acceptance.”

Though it is most closely associated with teenage girls, relational aggression is found in both girls and boys of all ages, though boys and younger girls tend to be more overt in their aggression. According to a new study in Child Development by University of Arizona professor Noel A. Card, boys are just as likely as girls to be relationally aggressive.